Streptococcus pneumoniae (hereinafter abbreviated as “S. pneumoniae” at times) is a causative strain of pneumonia, endocarditis, bacteremia, septicemia, meningitis, and otitis media. It is important for clinical studies and diagnoses to detect infection with S. pneumoniae by distinguishing such S. pneumoniae from other alpha hemolytic streptococci, which generally coexist with the above strain in human bodies.
Selection via culture and biochemical test methods, which utilize colony form, optochin sensitivity, bile solubility, seroreaction, and the like, have conventionally been used to detect and diagnose such infection with S. pneumoniae. 
However, when the aforementioned selection via culture is used in combination with the aforementioned biochemical test method, it takes 3 or more days until infection is determined. In addition, skilled techniques are necessary for precisely selecting its colony based on its form, a difference in color, and the like. Thus, without such skilled techniques, there has been a fear of interfering with clinical diagnosis and the subsequent treatments.
On the other hand, in recent years, a method of detecting S. pneumoniae using the PCR (polymerase chain reaction) method has also been proposed (Japanese Patent Application Laid-Open No. 9-327300). In the case of detection in which the PCR method is used, using primers specific to S. pneumoniae, nucleic acid is amplified with the collected DNA sample as a template, so as to detect the presence or absence of S. pneumoniae based on the presence or absence of such nucleic acid amplification. This method enables simple detection with certain reliability in a short time, when compared with the combined use of selection via culture and a biochemical test method.